The organic electroluminescent element (EL element) is recently attracting attention as a candidate for the flat panel display which emits natural light, has a high response speed, and has no dependence on viewing angle. Thus, the organic luminescent material constituting EL elements is arousing acute interest. The first advantage of the organic luminescent material is that its optical properties can be controlled to a certain extent by molecular design. This makes it possible to realize a full-color organic luminescent element made of luminescent materials emitting three primary colors (red, blue, and green) individually.
Styryl compounds represented by the following general formula [A] find use as an organic electroluminescent material and also find use in various applications because they emit intense light (ranging from blue to red in the visible region) depending on the substituent introduced thereinto. In addition, being sublimable, they offer the advantage of forming a uniform amorphous film by vacuum deposition. The present-day molecular orbital calculations permit one to make an approximate prediction of the material's optical properties. In actual, a technology to produce the desired material efficiently is most important for industry. (where, in the general formula [A] above, Ar represents an aryl group which may have a substituent, Ra and Rb each represent a hydrogen atom, a saturated or unsaturated hydrocarbon group, an aryl group which may have a substituent, a cyano group, a halogen atom, a nitro group, a hydrocarbon oxy group, or a hydrocarbon amino group, which may be identical or different.)
Organic luminescent materials produced so far are mostly those compounds represented by the general formula [A] above. Many of them emit light of blue to green, and only a few of them emit light of yellow to red. [The Institute of Electronics, Information and Communication Engineers; Technical Research Report; Organic Electronics, 17, 7 (1992), Inorganic and Organic Electroluminescence 96 Berlin, 101 (1996)] There has been no established method for their efficient production.